It has been found that an automobile travelling during daylight hours is much more readily visible to oncoming traffic if the headlights are turned on. However, upon stopping the automobile and turning the engine off, it is relatively easy to forget to turn off the headlights since they are not shining brightly against objects in front of the automobile. Additionally, during periods of fog or immediately preceding sunrise, one may wish to travel with the headlights on for safety purposes, but forget to turn them off upon reaching the destination. In these cases, if the driver is away from the automobile for any appreciable period of time, with the headlights burning, it is not uncommon for the battery to be dead and therefore one is unable to start the car upon returning. This can result in minor inconvenience and/or expense if aid is close, but may be extremely costly and time consuming if help must be summoned from a great distance.
Consequently, various methods for automatically turning off the headlights of motor vehicles have been proposed in the past, running the gamut from completely turning off the electrical system so that none of the lights or other electrically operated automobile accessories may function, to complex switching devices designed just to turn off the headlights.
U.S. Pat. No. 3,706,006, Miller, illustrates a lighting control device wherein a relay is connected in parallel with the conventional lighting system switch, so that when the engine is started a lighting switch responsive to the vehicle's generator energizes the relay, causing the parallel-connected contacts to turn the vehicle's lighting system on regardless of the position of the manually operated light switch. A further illustration of the prior light switch devices is U.S. Pat. No. 3,125,702, Herridge, Jr. et al, wherein a vacuum motor having a moveable diaphragm engages a manually operable switch shaft when the engine is running to maintain the headlights in an on position, and when the engine is turned off releasing the vacuum, the vacuum motor device releases the switch shaft, thereby turning off the lights. The vacuum motor may be manually overridden to operate the vehicle lights when the engine is not running. Similarly, U.S. Pat. No. 3,039,020, Sargent, discloses a switch wherein a shaft is manually disengaged from a vacuum operated diaphragm in order to turn on the vehicle lights. Once the automobile is started, the vacuum motor assembly compresses and engages the shaft to maintain the lights in an on position. Upon turning the automobile engine off, the diaphragm expands and pulls the shaft to the off position.
Conversely, U.S. Pat. No. 3,206,637, Finken, discloses a system whereby parking lights are prohibited from being operated while the vehicle is moving. The parking light circuit is connected to the transmission selector lever so that the parking lights may not operate when the lever is in a drive position. U.S. Pat. Nos. 3,021,449, Kerr et al, 3,058,030, Simpkins and 2,045,274, Kundig are examples of headlight switching devices not considered especially relevant to the present invention.